Nigeria’s former president warned investors at an African business summit in London they should focus on promoting “inclusive growth” if they want to avoid triggering social strife.

Olusegun Obasanjo, who was president of Nigeria from 1999 to 2007 was speaking at the Global African Investment Summit to about 450 people who were considering the merits of 136 African investment projects worth $246 billion.

“Old practices are no longer acceptable,” said the former president, who chaired the two-day investment meeting. “Today, we expect our partners to place the social and economic development of our citizens at the forefront of their projects’ design.”

Mr. Obasanjo added: “Our projects offer some of the best rates of return anywhere in the world and in return we want the best technology, cheaper finance and a greater commitment to our social and economic welfare. We want you to source locally and to actively grow supply chains in our countries. Value addition is the key.”

The former president acknowledged there have been setbacks on the continent, such as the rise of the Boko Haram terror group in Nigeria and al-Shabaab in East Africa, as well as conflict in South Sudan and the Ebola outbreak in West Africa. However, he said the overall trajectory of the continent is “overwhelmingly positive.”

Former U.K. foreign minister William Hague told investors that private equity funds could help fill a funding gap that is holding back the development of infrastructure in Africa.

“The gap cannot be plugged by government expenditure alone,” Mr. Hague said. “Investors are still quite tentative. Changing perceptions takes time but an improved track record of political stability in many countries is helping.”

President John Mahama of Ghana described Africa as full of opportunities for investors, from infrastructure to energy, tourism, transport and hospitality. Taking a different tack than most leaders aiming to attract investment, he pointed out that his children have no amusement park to visit in his country’s capital, which could provide investors one opportunity.

“We have no light industry and manufacturing,” President Mahama added. “China and Asia are beginning to become high-cost areas because wages and salaries are going up. People who are interested in electronics and light manufacturing probably should be looking to Africa now to move their production there.”

Mr. Obasanjo summed up his sales pitch for the continent, noting the opportunities in Africa are “electrifying.”

However, Uganda is one country where opportunities for investors may literally not be electrifying. Ugandan president Yoweri Museveni surprised investors on Monday by saying he’d prefer them to stay away from building power plants in his country, where Blackstone Group built a hydroelectric dam, unless they can lower their electricity fees.